Extreme pressure lubricants



Uilifi. States Patent nxrnnnm runssoan LUBRICANTS George Wolfram, Des Plaincs, and Allan Mantculiel,

Union, BL, assignors to The Pure Oil Company, Chicage, Ill., a corporation of Ohio N Drawing. Application August 1, 1952 Serial No. 302,232

8 Claims. (Cl. 252-465) This invention relates to compositions useful for lubricating mechanical elements subject to extreme pressures and to methods of preparing same.

In the lubrication of gear elements in automotive vehicles, lubricating oils are generally used which are fortified with additives to impart to the lubricating oil the ability to lubricate at high pressures. One such product which has been in successful use for many years is a sulfurized-phosphorized lard oil such as that disclosed in Whittier et a1. Patent No. 2,211,306.

Although the product made in accordance with this patent gives excellent results, it has several shortcomings. It is not universally soluble in all types of lubricating oils. Moreover, when blended in finished oil, the oil does not have a sufiiciently low channel point to enable it to be used under very low temperature conditions; and a further disadvantage is that it cannot be blended into finished oil to meet the proposed new SAE specifications for combination 75/80 grade and 80/90 grade lubricating oils.

Although sulfurized-phosphorized fatty bodies, such as sulfurized-phosphorized propylene glycol dioleate and glyceryl trioleate, have been developed which have overcome some of the shortcomings of sulfurized-phosphorized lard oil, these products are too expensive to be competitive in all markets with competitive products available for these purposes. As a result, it has been found necessary to market different products in different sections of the country to meet the conditions present in each section.

The present invention. overcomes existing problems by formulating a single additive which is equal in performance to known types of sulfurized-phosphorized additives heretofore developed, and which has the further quality of being universally soluble in different types of mineral lubricating oils. The additive of our invention is also stable, i. e., it does not form sedimentation upon standing, and imparts to the lubricating oil to which it is added a low channel point thereby making it suitable for use under low temperature conditions. Furthermore, lubricants in which our novel additive is incorporated can be blended to meet the proposed new combination SAE /80 and /90 grade specifications.

We have discovered that by separately sulfurizing Metalyn (a methyl ester of tall oil acids) or other esters of tall oil acids and the lower straight chain saturated monohydric aliphatic alcohols and phosphorizing a substance from the group of glyceryl trioleate, ethylene, propylene, butylene glycol dioleate, and low polyunsaturate lard oil, the two products can be combined to form an additive which, when added to lubricating oil, imparts thereto the desirable characteristics hereinabove set forth. Low polyunsaturate lard oil asusedin the appended claims is lard oil which has been solvent extracted to remove substantially all of those compounds having two or more unsaturated bonds in the acid radical. Whereas it has been the general practice to sulfurize and phosphorize the same fatty body in. orderto. make ice an extreme pressure additive, in the case of Metalyn and homologous esters, this cannot be done since phosphorization results in polymerization and production of an unsatisfactory product. But, by separately sulfurizing the tall oil esters and phosphorizing the glyceryl trioleate or equivalent material, sulfur and phosphorus reaction products are produced which can be blended readily to form a suitable additive. By proper selection of mineral lubricating oil stocks to give the desired viscosity, the required specifications for any SAE grade lubricant can be readily obtained.

We have found that the esters of tall oil acids in which the replaceable hydrogen has been substituted by branched chain alkyl groups such as isopropyl and isobutyl are not satisfactory because they do not produce stable molecules and have a tendency to polymerize.

By far the major portion of the additive in accordance with our invention consists of the sulfurized tall oil ester. Metalyn is a readily available low cost material and for that reason we prefer it to the other esters of tall oil acids and aliphatic monohydric alcohols. Since the sulfurized Metalyn is' a relatively low cost material as compared to phosphorized glyceryl trioleate which is added in only minor amounts, the resulting cost of the additive and the finished oil is comparable to that of sulfurizedphospho-rized lard oil.

On the basis of stability, i. e., lack of sedimentation upon standing and E. P. bench test results (Timken and Modified S. A. E.) the phosphorized glyceryl trioleate is superior to the other phosphorus carriers.

Metalyn is a trade name for methyl esters of tall oil acids, and it is prepared by the methyl alcohol esterification of tall oil acids under elevated pressure followed by distillation of the ester. This product, now being manufactored by the Hercules Powder Company, will have the following characteristics:

45.0 (typical). 47.0 (typical).

Percent methyl esters of rosin acids Percent methyl esters of fatty acids Specific gravity 20/20 C .95/.975.

Flash point, C. (COC) 182 min. Freezing point, C max. Viscosity at 100 F, SUS (ASTM D445-46T) 70/ M10. Moisture (AOCS Ca 221 5) 0.1max. Appearance at 20/30 C Clear and free of foreign matter.

In sulfuriziog the Metalyn, elemental sulfur in the form of finely powdered flowers of sulfur is sifted in small increments into a kettle containing the Metalyn heated to about 275 to 285 F., while being vigorously agitated by a mechanical agitator. Although we prefer to react 93 parts of Metalyn with 7 parts by weight ofsulfur, the ratio of Metalynto sulfur may suitably vary from about 35 parts Metalyn--l5 parts sulfur to 97 parts Metalyn-3 parts sulfur.

After the addition of the sulfur to the Metalyn is completed, the temperature of the mixture is raised to 350 F. During the initial stages of the sulfurization reaction, it is important to keep the temperature about 20 to 30 below the dash point of Metalyn (385 F.). Reaction is allowed to proceed for approximately 7 to 8 hours when it should be complete as indicated by a copper strip test. Shorterreaction periods are, possible where,

chanical agitation and not air-blowing is used during the entire reaction period. The finished reaction product will have the following characteristics:

API gravity 8.0 Lbs. per gallon 5. 8.45 Percent sulfur 6.26

SUS viscosity at 210 F 56.2

Although this is the preferred product, it will be understood that the sulfurized Metalyn may contain from approximately 3 to 10 percent of sulfur. Where smaller amounts of sulfur are used, the reaction time and/or temperature may be reduced. Similarly, where larger amounts of sulfur are used, longer reaction times will be required in order to obtain a finished product. Higher temperatures will hasten the reaction time, but temperatures in excess of 400 F. should be avoided.

It will be understood that other esters of tall oil acids such as the. ethyl, propyl, butyl, and amyl may be sulfurized in the same manner as Metalyn to form one constituent of the E. P. base. If desired mixtures of the several esters may be used instead of a single ester in order to obtain desired viscosity, pour point, and other properties in the finished oil.

We prefer to use glyceryl trioleate as the phosphorus carrier because of its superior load carrying ability. In preparing the phosphorized glyceryl trioleate, we prefer to use glyceryl trioleate having the following specifications:

80% oleic min. 12% linoleic max. 8% saturated max.

Phosphorus sesquisulfide is used for phosphorization because of the uniformity of the resulting products. Other sulfides of phosphorus such as phosphorus pentasulfide cause undesirable polymerization. It is important that a pure form of phosphorus sesquisulfide be used since impure material produces a dust-like sediment in the finished product. Pure phosphorus sesquisulfide has a uniformly light yellow color, while the impure material is characterized by small particles of grayish material running uniformly through the entire sample.

In our preferred method of phosphorizing glyceryl trioleate, we heat 195 parts by weight of glyceryl trioleate in a kettle to 185 to 195 F. with vigorous me chanical agitation. To the heated material is added parts by weight of finely powdered phosphorus sesquisulfide in small increments. When the total amount of phosphorus sesquisulfide is added, the temperature of the mixture is raised to 220 to 230 F. and the temperature maintained at this level until the reaction is complete, which should require about 4 to 5 hours. The completion of the reaction is determined by immersing a copper strip in a sample of reaction mixture at the temperature of 210 F. for 3 minutes. If the strip remains bright, the reaction is completed. During the entire reaction, mechanical agitation, and .not air-blowing, is

asranse used. The finished phosphorized glyceryl trioleate will have the following characteristics:

API gravity 19.7

Lbs. per gallon 7.79 Weight percent sulfur 0.97 Weight percent phosphorus 1.26

SUS viscosity at 210 F 67.7

It will be understood that the amount of phosphorus sesquisulfide incorporated in the product may vary somewhat from the optimum amount above specified, and may range from an amount equivalent to 0.6 to 2.5 per cent phosphorus.

Phosphorized ethylene, propylene, and butylene glycol oleate or phosphorized low polyunsaturate lard oil are prepared in the same manner as the phosphorized glytive which produces excellent results. A blend of 5 parts of sulfurized Metalyn with 1 part of phosphorized glyceryl trioleate prepared and having the characteristics as above set forth will produce an additive having the following characteristics:

API gravity 10.1'

Lbs. per gallon 8.32 Weight percent sulfur 5.35 Weight percent phosphorus 0.21 SUS viscosity at 210 F 58.4

Although this is the preferred additive, it will be understood that suitable additive blends can be prepared having a sulfur content of approximately 2.5 to 8 percent by weight of sulfur and a phosphorus content of between 0.1 and 0.4 percent by weight by mixing one or more of the aforesaid sulfurized tall oil acid esters with one or more of the aforesaid phosphorus carriers.

In blending the additive into finished lubricating oil, we may use approximately 10 to 30, but preferably 12 to 15 percent by weight of the additive, so that the finished oil contains approximately .02 to .06 percent of phosphorus and approximately .5 to 1.5 percent of sulfur derived from the additive.

Two blends of finished lubricating oil were prepared having the following compositions:

Blend No. l Blend No. 2

12% wt. 83% Sullurized Metalyn, 16% Phosphorized glyceryl trioleate.

0.5% wt. Acryloid (A blend of polymerized esters of methacrylic acid and higher molecular weight alcohols).

60% wt. Lubricating Oil H.

26.5% wt. Lubricating Oil L.

15% wt. 83% Sulfurized Metalyn, 16% Phosphortzed glyceryl trioleate.

0.5% wt. Acryloid 150.

57.0% wt. Lubricating Oil H.

26.5% wt. Lubricating Oil L.

ing the following characteristics:

index lubricating oils prepared by solvent extraction of Mid-Continent type petroleum lubricating oil fractions with phenol were used. This oil meets all the require.-

Lubflcat. ments for a combination SAE 80/90 grade extreme presing 3 h1g0 L sure lubricant.

g r r o avity 24.; 29. 3 Composition, percent by weight:

35 6 F 353 Sulfurized Metalyn Vis. at 210 F.-57.2

SUS viscoslty Phosphorized glyc- Percent 8-5.30 15.0

100 F 2, 939 202 P I 0 g 1,049 105,; eryl trioleate ercent P--0.18i V1 6 Dibenzyl dtsulfide 1.0

o inera u ricatmg o1 i i iii s iiiriiiii i iifi fi ii ii ii iii n ral lu a n o l B 56-0 Characteristics:

Viscosity at-- The results obtained on the Mil L-2105 performance 100 F 744 tests on the 15% blend are given in the following table 210 F. 81.5 as compared with the Mil L-2l05 specifications for the Index 109 90 grade oil: Viscosity extrapolated at 0'F 75,000

Tests on Military L-e105 E. P. blends Blend Designation Blend No. 51- 276 Specification Mil L-2105 SAE Grade 90 00. Percent by weight Composition 15% (5 nts. suli'urized Metalyn; 1 I v i I pt. phosphorized glyceryl tri- 0.5% Aeryloid 150; 57.0% Lube H; 26 5% Lube L). y API Gravity Flash, F 325 SUS, Viscosity:

210 F. 80-90. viscosity lnrlev V 85 Min.

Pour Point, F. Channel Point, F 0 F. Max. Percent Phosphorus. 0 Percent Chlorine- Percent Lead i Percent Sulfur Total R (Very) Light..- Pass. CBC L13 Copper S Light Peacock Pass. SAE/1,000 R. P. M-.. 130 SA E/500 R. P. M. (after heating) 'Iimken:

Beam...

Pressure 0R0 L-20 Dynamometer Test Pass (one).

(High Torque-Low Speed test using D0 Ton 9% Hypoid Axle mm 30 Pinion. Gear Ring Gear hours-at 200 to 250 I oil temp., 32,311 lb. in torque at 62 R. P. M.) Dull hnrnish Dull .burnish l i Light Wear Light Wear Cooling cycle 23 to 31 Minutes I ORG L-19 Dynamometer Test Pass Pass (In dnpli- (High Speed test using a new Chevrolet hypoid 3rd Member assembly, 9-37 1st Run: No scoring of teeth eate).

ratio 111: a dynalnolneter installation to simulate a Chevrolet passenger 2nd Run: No scoring of teeth ve ee (a) Break in 5 miles at 25 M. P. H. and 151i). lead. (0) Accelerate to 40 M. P. H. with 0 lb. load, then coast from 40 M. I. H. and lb. load to 10 M. P. H. with clutch engaged (tot. 4 times). (c) Accelerate from 60 to M. P. H. with 0 lb. load and coast from 80 032;. ES. and 1b. load to 60 M. P. H. with clutch engaged (total of lines CRO L-Zl Moisture-Corrosion Test Pass Pass. 28 cc. of Water in 3 pints of lubricant r 2,400 R. P. M. 4 hrs/180 F. and 10 days at R. T ORC L-12 Foam Test Pass Sequence (1) Room Temp 550 cc 650 cc. Max.

Sequence (2) 200 F i cc 050 cc. Max. CRO IP22 Storage Solubility and Compatibility Tests Pass Pass.

30 days at room temp N o Residue-.-

. No Incompatibility...

This blend not only passes Mil L-2105 specifications ASTM pour, F 25 for 90 grade oil, but passes all specifications for a SAE Channel point, F a- 30 80 grade oil except the 100,000 maximum SUS viscosity Storage stability O. K. at 0 F. This specification can be readily met by use 70 Modified SAE- of high viscosity index lubricating oil stocks instead of Ring condition O. K. intermediate viscosity index stocks used in the prepara- Ring wt. loss, mg 20.6 tion of the blend which was tested. Timken-- The following table gives the properties and composi- Beam load 51 tion of an E. P. lubricating oil in which high viscosity 75 Pressure 32,050

Characteristics API cn it ni Percent Sulfur Acid No 0.2

2,416,504. By blending the various constituents together into a single additive, a low cost all purpose additive may be prepared which can be blended with any type mineral lubricating oil to give it excellent extreme pressure properties which will meet either or both commercial and military requirements, thereby avoiding the necessity of manufacturing and handling several different additives.

It will be understood that the specific blends given by way of example are not necessarily the cheapest or best blends. By varying the quantities of sulfurized Metalyn or equivalent and phosphorus glyceryl trioleate or equivalent in the additive or finished oil, a product meeting necessary requirements for the use intended may be made at minimum cost; or a product of maximum oiliness and load carrying ability can be arrived at if cost is not a determining factor. The glyceryl trioleate, ethylene, propylene, and butylene glycol dioleates and low polyunsaturate lard oil, in addition to acting as phosphorus carriers, are oiliness agents and contribute unexpectedly to the load carrying ability of the finished additive. Therefore where cost is not important, larger amounts of the phosphorus carrier may be incorporated in the additive or finished oil.

What is claimed is:

1. An extreme pressure lubricant additive consisting essentially of (a) 3-5 parts by weight of a sulfurized ester of tall oil acids and a straight chain C -C aliphatic, saturated, monohydric alcohol, said sulfurized ester containing 3-10% by weight of sulfur, and (b) 1 part by weight of the reaction product of phosphorus sesquisulfide and a substance selected from the group consisting of glyceryl trioleate, ethylene glycol dioleate, propylene glycol dioleate, butylene glycol dioleate, and a lard oil containing a low content of polyunsaturated constituents, said reaction product having a phosphorus content of 0.6-2.5 wt. percent.

2. An extreme pressure lubricant additive consisting essentially of (a) 3-5 parts by weight of a sulfurized ester of tall oil acids and methyl alcohol, said sulfurized ester containing 3-10% by Weight of sulfur, and (b) 1 part by weight of the reaction product of phosphorus sesqui- 8 sulfide and a substance selected from the group consisting of glyceryl trioleate, ethylene glycol dioleate, propylene glycol dioleate, butylene glycol dioleate, and a lard oil containing a low content of polyunsaturated constituents, said reaction product having a phosphorus content of 0.6-2.5 wt. percent.

3. An extreme pressure lubricant additive consisting essentially of (a) 3-5 parts by weight of a sulfurized ester of tall oil acids and methyl alcohol, said sulfurized ester containing 3-10% by weight of sulfur, and (b) 1 part by weight of the reaction product of phosphorus sesquisulfide and glyceryl trioleate, said reaction product having a phosphorus content of 0.6-2.5 wt. percent.

4. An extreme pressure lubricant additive consisting essentially of (a) 3-5 parts by weight of a sulfurized ester of tall oil acids and methyl alcohol, said sulfurized ester containing 6.26% by weight of sulfur, and (b) 1 part by weight of the reaction product of phosphorus sesquisulfide and glyceryl trioleate, said reaction product having a phosphorus content of 1.26 wt. percent.

5. A lubricant comprising a major portion of a mineral, lubricating oil and containing 10-20% by weight of an extreme pressure lubricant additive consisting essentially of (a) 3-5 parts by weight of a sulfurized ester of tall oil acids and a C -C straight chain, aliphatic saturated monovalent alcohol, said sulfurized ester containing 3-1()% by weight of sulfur, and (b) 1 part by weight of the reaction product of phosphorus sequisulfide 'and a substance selected from the group consisting of glyceryl trioleate, ethylene glycol dioleate, propylene glycol dioleate, butylene glycol dioleate, and a lard oil containing a low content of polyunsaturated constituents, said reaction product having a phosphorus content of 0.6-2.5 vvt. percent.

6. A lubricant in accordance with claim 5 in which said additive is present in amounts sufiicicnt to incorporate 0.02-0.06% phosphorus, and 0.5-1.5% sulfur in the lubricant.

7. A lubricant comprising a major portion of a mineral, lubricating oil and containing 10-20% by weight of an extreme pressure lubricant additive consisting essentially of (a) 3-5 parts by weight of a sulfurized ester of tall oil acids and methyl alcohol, said sulfurized ester containing 3-10% by weight of sulfur, and (I1) 1 part by weight of the reaction product ofphosphorus sesquisulfide and glyceryl trioleate, said reaction product having a phosphorus content of 0.6-2.5 wt. percent, said additive being present in amounts sufficient to incorporate 0.02-0.06% phosphorus, and 0.5-1.5% sulfur in the lubricant.

8. A lubricant in accordance with claim 7 in which is incorporated 5-10% by weight of dibenzyl disulfide.

References Cited in the file of this patent UNITED STATES PATENTS 2,204,538 Lincoln et al. June 11 1940 2,242,260 Prutton May 20, 1941 2,318,630 Prutton May 11, 1943 2,542,161 Stucker Feb. 20, 1951 OTHER REFERENCES Zuidema: The Performance of Lubricating Oils, Reinhold Publishing Corp., N. Y., 1952, pp. 12 and 15. 

1. AN EXTREME PRESSURE LUBRICANT ADDITIVE CONSISTING ESSENTIALLY OF (A) 3-5 PARTS BY WEIGHT OF A SULFURIZED ESTER OF TALL OIL ACIDS AND A STRAIGHT CHAIN C1-C5 ALIPHATIC, SATURATED, MONOHYDRIC ALCOHOL, SAID SULFURIZED ESTER CONTAINING 3-10% BY WEIGHT OF SULFUR, AND (B) 1 PART OF WEIGHT OF THE REACTION PRODUCT OF PHOSPHORUS SESQUSULFIDE ADN A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF GLYCERYL TRIOLEATE, ETHYLENE GLYCOL DIOLEATE, PROPYLENE GLYCOL DIOLEATE, BUTYLENE GLYCOL DIOLEATE, AND A LARD OIL CONTAINING A LOW CONTENT HAVING A PHOSPHORUS CONTENT OF 0.6-2.5 WT. PERCENT. 